1. Field of the Invention
The present invention relates to a process of selective area chemical vapor deposition of metal film.
2. Description of the Related Art
It has recently been desired to establish a process of selective chemical vapor deposition of Au, Pt or other metals having low electrical resistivity, good corrosion resistance, and X-ray impermeability to advantageously provide conductor wirings of integrated circuits, contact holes of multiple layered conductor wirings, and masks for X-ray exposure.
Paul F. Seidler et al., in "Low Temperature Selective Chemical Vapor Deposition of Gold Films: Growth and Characterization", 1992 Mat. Res. Soc. Symp. Proc., proposed a process of selective chemical vapor deposition of a gold film using a catalytic reaction of a selective area in which the gold film is formed.
FIG. 1 clarifies the proposed conventional process of selective chemical vapor deposition of gold films, in which the axis of abscissa indicates the film growing temperature and the axis of ordinate indicates the film growth rate.
The conventional process of selective chemical vapor deposition of gold films provides selectivity between a Au substrate and an SiO.sub.2 or other insulating substrate or selectively between a Cu substrate and an SiO.sub.2 or other insulating substrate at film growing temperatures in the range of 30.degree. to 109.degree. C., in which the growth rate of gold film is merely 30 .ANG./min at most and is not suitable for practical applications. Thus, it is not practical to grow a film of gold or other inactive metals by conventional chemical vapor deposition, in which a source is decomposed by a catalyst provided in a selective area to precipitate the metal, because of the inefficiency due to the small growth rate such as 30 .ANG./min at most as recited above.
This is because the chemical vapor deposition of Au or other inactive metals using a process providing high selectivity requires that the reaction rate be small even in the nonselective area (i.e., the area other than the selective area), which in turn requires that the growth rate also be small in the selective area.